The present invention relates to an interframe encoding system for video signals.
As a high-efficiency encoding system for video signals, there is known an interframe encoding system. In the interframe encoding system, since the quantity of information to be encoded varies from moment to moment with changes in the scene which video signals constitute, a buffer memory is provided at the output of the encoding system for transmitting encoded signals at a constant rate through a transmission line. In order to avoid overflowing or underflowing of this buffer memory, the generation of encoding information has to be controlled by feeding back to the interframe encoder the data occupancy within the buffer memory (buffer occupancy quantity). Furthermore, such an interframe encoding system is equipped with a code converter for two-dimensional run length encoding or block encoding of encoded signals for the purpose of acheiving even higher efficiency in encoding.
However, while two-dimensional run length encoding requires conversion of encoded signals by a two-dimensional scanning method, such scan conversion, for instance the block size of n picture elements by m lines, would result in a delay by the length of time corresponding to m lines and therefore delay between the interframe encoder and the buffer memory arises during scan conversion. As a consequence, there is the disadvantage that the buffer occupancy quantity fedback to the interframe encoder is less by the quantity of information which is under scan conversion and, accordingly, the generation of encoding information cannot be controlled accurately.